Any aftermarket alternatives?

 

If the stick is in such bad shape, it's time to replace the tank.

The level sensor is a reed switch that's operated by a magnet, presumably attached to the bottom of the float. So long as the float still floats, the level sensor should still work.

 

The same thing happened to my coolant level indicator stick; it just broke into pieces. I had to buy a new coolant expansion tank, BMW part # 17137542986. The install was easy with the hose quick disconnect. Good luck .

 

Incidentally, when the float bumps up to the top of its travel, the tank is full. So the float is usable as a level gauge until you have a chance to change out the tank.

 

My 2007 530i kept giving me an error mssg = low coolant level. I added coolant three times over 2 months before I took it in for repair under warranty. I was sure it was the expansion tank since this is such a problem for BMW's, but it turns out it was the radiator that was leaking. They replaced the radiator under warranty. The moral is if your stick is falling apart you probably are due for a new expansion tank, but if you're getting a low coolant level error you need to identify the leak before replacing the expansion tank. You might need that extra cash for a new radiator which I'm sure isn't cheap! The expansion tank could still be pretty well intact and can wait. It's already over 100 degrees everyday in AZ, and the last place I want to be is on the side of the freeway overheating with a brand new tank and a busted radiator! Just an fyi...